Restructured the project structure back to the way it was, there's no reasonable way to split the modules

src/NadekoBot/Modules/Music/_common/Impl/VoiceProxy.cs

@@ -0,0 +1,102 @@
+#nullable disable
+using Ayu.Discord.Voice;
+using Ayu.Discord.Voice.Models;
+
+namespace NadekoBot.Modules.Music;
+
+public sealed class VoiceProxy : IVoiceProxy
+{
+    public enum VoiceProxyState
+    {
+        Created,
+        Started,
+        Stopped
+    }
+
+    private const int MAX_ERROR_COUNT = 20;
+    private const int DELAY_ON_ERROR_MILISECONDS = 200;
+
+    public VoiceProxyState State
+        => gateway switch
+        {
+            { Started: true, Stopped: false } => VoiceProxyState.Started,
+            { Stopped: false } => VoiceProxyState.Created,
+            _ => VoiceProxyState.Stopped
+        };
+
+
+    private VoiceGateway gateway;
+
+    public VoiceProxy(VoiceGateway initial)
+        => gateway = initial;
+
+    public bool SendPcmFrame(VoiceClient vc, Span<byte> data, int length)
+    {
+        try
+        {
+            var gw = gateway;
+            if (gw is null || gw.Stopped || !gw.Started)
+                return false;
+
+            vc.SendPcmFrame(gw, data, 0, length);
+            return true;
+        }
+        catch (Exception)
+        {
+            return false;
+        }
+    }
+
+    public async Task<bool> RunGatewayAction(Func<VoiceGateway, Task> action)
+    {
+        var errorCount = 0;
+        do
+        {
+            if (State == VoiceProxyState.Stopped)
+                break;
+
+            try
+            {
+                var gw = gateway;
+                if (gw is null || !gw.ConnectingFinished.Task.IsCompleted)
+                {
+                    ++errorCount;
+                    await Task.Delay(DELAY_ON_ERROR_MILISECONDS);
+                    Log.Debug("Gateway is not ready");
+                    continue;
+                }
+
+                await action(gw);
+                errorCount = 0;
+            }
+            catch (Exception ex)
+            {
+                ++errorCount;
+                await Task.Delay(DELAY_ON_ERROR_MILISECONDS);
+                Log.Debug(ex, "Error performing proxy gateway action");
+            }
+        } while (errorCount is > 0 and <= MAX_ERROR_COUNT);
+
+        return State != VoiceProxyState.Stopped && errorCount <= MAX_ERROR_COUNT;
+    }
+
+    public void SetGateway(VoiceGateway newGateway)
+        => gateway = newGateway;
+
+    public Task StartSpeakingAsync()
+        => RunGatewayAction(gw => gw.SendSpeakingAsync(VoiceSpeaking.State.Microphone));
+
+    public Task StopSpeakingAsync()
+        => RunGatewayAction(gw => gw.SendSpeakingAsync(VoiceSpeaking.State.None));
+
+    public async Task StartGateway()
+        => await gateway.Start();
+
+    public Task StopGateway()
+    {
+        if (gateway is { } gw)
+            return gw.StopAsync();
+
+        return Task.CompletedTask;
+    }
+}